Method of making a magnetic head with aligned pole tips and pole layers formed of high magnetic moment material

ABSTRACT

A method of making a magnetic head which includes first and second pole tip layers separated by a nonmagnetic gap layer includes making the pole tips of a high magnetic moment material. The right side walls of the first and second pole tips are vertically aligned with each other. Similarly, the left side walls of the first and second pole tips are vertically aligned with one another. The side fringing flux from one pole tip to another is substantially reduced resulting in a magnetic head capable of writing data tracks with well defined boundaries. The possibility of the pole tips operating in magnetic saturation is reduced because the pole tips, formed of high magnetic moment material, is capable of accommodating high coercive force. The magnetic head can be fabricated as an inverted head or a non-inverted head capable of writing on magnetic media with high coercivity and at a high data transfer rate.

FIELD OF THE INVENTION

This invention relates to the method of making magnetic heads havingnarrow pole widths with high saturation threshold levels capable ofwriting on magnetic media with high areal densities and coercivity.

BACKGROUND OF THE INVENTION

A typical inductive thin film magnetic head comprises a first magneticpole layer and a second magnetic pole layer with an electrical coilbetween the two pole layers. The two pole layers contact each other atone end at a back closure to form a continuous magnetic path, with anarrow transducing gap at the other end. The portions of the first andsecond poles separated by the transducing gap are designatedrespectively as the first and second pole tips. In order to write datawith narrow track widths and high linear recording densities, it isnecessary to provide a magnetic head with narrow pole tips. However,there are technical problems associated with fabricating a magnetic headwith narrow pole tips. A key problem confronted during manufacture isthe alignment of the two pole tips. Various methods have been suggestedto solve this problem.

The magnetic head described above is called an inductive head. Theinductive head can be combined with a data reading transducer to form amerged head.

FIG. 1 shows a prior art approach in which a magnetic head 2 isfabricated with a first pole tip 4 wider in lateral dimension than asecond pole tip 6. The wider first pole tip 4 tolerates a certain degreeof misalignment during the deposition of the second pole tip 6. In themagnetic head 2, the width TW of the second pole tip 6 is intended todefine the track width of the magnetic head 2. However, the problem withthis approach is that due to the larger width of the first pole tip 4,magnetic flux fringing beyond the width of the second pole tip 6 isunavoidable. The fringing flux, such as flux lines F emanating from thesecond pole 6 to the first pole 4 as shown in FIG. 1A, would result inregistering a data track 8 with a width W having ambiguous trackboundaries, which seriously limit the track-to-track separations on therecording medium 10.

Modern day storage products are now built with ever decreasing physicalsizes and increasing storage capacities. Magnetic heads are fabricatedon microscopically confined areas. To increase the sensitivity of themagnetic head, the number of coil windings can be increased. However,any increase in coil windings is restricted by the confined areas.Furthermore, the higher the number of coil windings, the higher is theresultant inductance attached to the magnetic head. A magnetic head withhigh inductance is sluggish in response to data writing current andincapable of operating at high frequency ranges.

Another approach to increase the writing sensitivity of the magnetichead is to increase the magnitude of the writing current. Higher writingcurrent generates higher Joule heat which increases the burden of themagnetic heat formed in a confined space in respect to the heatdissipation. However, an overriding issue is the premature magneticsaturation encountered by the magnetic yokes in response to higherwriting current.

FIG. 2 shows the hysteresis curve 12 of a magnetic material such asPermalloy (NiFe) which includes a high permeability slope of the curve12 and low coercivity H_(c). Because of these characteristics, Permalloyis commonly used as the material for the magnetic yokes or tips ofmagnetic head. FIG. 2A is a fragmentary view of the conventionalmagnetic head 2 at the tip portion. When the writing current I passingthrough the coil 14 increases, the magnetic flux induced by theinductive coil 14 also increases. The magnetic flux which exertscoercive force on the magnetic yoke layers 16 and 18 also increases. Forexample, as shown in FIG. 2, when the coercivity exceeds 5 Oersteds, themagnetic yoke layers are fully saturated at 200 nanowebers and can nolonger be responsive to any increase in writing current. Normally,magnetic saturation happens at the areas with the smallest physicaldimensions. For instance, when magnetic saturation occurs, it firsttakes place at the first and second tip layers 4 and 6 and then slowlyprogresses to the areas with larger physical bulk, such as the yokebodies 16 and 18. With pole tips built smaller for the purpose ofwriting narrow data tracks, the problem of magnetic saturation isfurther exacerbated.

Magnetic heads with pole tips having vertically aligned sidewalls havebeen proposed. U.S. Pat. No. 5,452,164, Cole et al., entitled "The ThinFilm Magnetic Write Head", issued Sep. 19, 1995 discloses a magnetichead in which the vertically aligned sidewalls of the first and secondpole tips are made possible by the process of ion milling through anoverlying mask as a template. However, the magnetic head of Cole et at.does not address the magnetic saturation problem.

The problem of obscure data track boundaries written by a magnetic headand the problem of preventing the magnetic head from operating inpremature saturation, when the head is built with a smaller physicalsize, need to be addressed. The problems are more intensified as storageproducts are now built with further reduced sizes and increased storagecapacities. Data tracks written with ambiguous track boundariesseriously undermine track-to-track separations which in turn compromisethe overall storage capacity of storage devices. A prematurely saturatedmagnetic head is incapable of operating at high frequency and is ineptin performing high rate data transfer onto media with high arealdensities. Accordingly, there has been a need to provide magnetic headscapable of writing data tracks with well defined track boundaries, yetmade available at reasonable manufacturing costs.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a method of making amagnetic head, in which it is capable of writing narrow data tracks withhigh linear recording densities.

It is another object of the invention to provide a method of making amagnetic head having a high saturation threshold capacity and capable ofperforming high data rate transfer onto media with high coercivities andhigh areal densities.

According to this invention, a thin film magnetic head includes firstand second pole tips separated by a nonmagnetic gap layer. The pole tipsare made of a high magnetic moment material. The right side and leftside walls of the first and second pole tips are vertically aligned witheach other respectively. The side fringing flux of one pole tip toanother is substantially reduced resulting in a magnetic head capable ofwriting data tracks with well defined boundaries. Furthermore, thepossibility of the pole tips running into magnetic saturation is reducedbecause the pole tips, made of high magnetic moment material, aretolerant of high coercivity media.

The magnetic head of the invention can be fabricated as an inverted or anoninverted head. In either case, the aligned pole tips are first madeby depositing a tri-layer sandwich having a gap layer between the firstpole layer and the second pole layer on the substrate. The tri-layersandwich is then etched away through a masking layer, thereby leaving atleast a stack of layers formed on the substrate. The stack of layersconstitutes the magnetic pole tip region of the magnetic head withaligned sidewalls for the pole tips. In accordance with the invention,the pole tips can be narrowly defined, thereby allowing the inventivehead to write on magnetic media with narrow data track widths. Theproblem of premature magnetic saturation is avoided because the poletips are made of high magnetic moment material.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail with reference to thedrawings in which:

FIG. 1, as described above, is a cross-sectional front view of a priorart magnetic head having the first pole tip wider in lateral dimensionthan the second pole tip which is characterized by misalignment of thesecond pole tip during fabrication;

FIG. 1A schematically illustrates the effect of the side fringing fluxon a registered data track written by the conventional magnetic head asshown in FIG. 1;

FIG. 2 is an hystersis characteristic of a ferromagnetic material usedin a conventional magnetic head;

FIG. 2A is a fragmentary view of the magnetic head shown in FIG. 1illustrating the tendency of the magnetic head of running into magneticsaturation starting from the pole tip region;

FIG. 3 is a top plan view, partly broken away, of an embodiment of theinvention fabricated as a non-inverted head;

FIG. 4 is a cross-sectional front view taken along the line 4--4 of FIG.3;

FIG. 5 is a cross-sectional side view taken along the line 5--5 of FIG.3;

FIGS. 6A-6S are sequential views schematically illustrating the processof forming the magnetic head of the invention as shown in FIGS. 3-5;

FIG. 7 is a cross-sectional front view, shown in part, of anotherembodiment of the invention fabricated as an inverted head;

FIG. 8 is a cross-sectional front view taken along the line 8--8 of FIG.7; and

FIGS. 9A-9N are sequential views schematically illustrating the processof forming the magnetic head of the invention as shown in FIGS. 7-8.

Like reference numerals refer to like parts throughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 shows the top plan view of a magnetic head 20, made in accordancewith this invention. For the sake of clarity in illustration, the topprotective and insulating layers in FIG. 3 are not illustrated so as toexpose the relevant components of the magnetic head 20. However, the toplayers are shown in FIGS. 4 and 5 which are cross-sectional front andside views taken along the lines 4--4 and 5--5, respectively, of FIG. 3.

The magnetic head 20 includes a first yoke layer 22 formed with a firstpole tip layer 26 and disposed on a substrate 24. The substrate 24 canbe made of a non-magnetic and electrically insulating material, such asalumina titanium carbide (Al₂ O₃ TiC) or silicon carbide (SiC). Thesubstrate 24 can be pre-fabricated with components. For example, in amerged head, various component layers, such as a first shield layer 38and a read transducer 39, may be fabricated in advance and thereafterserve as a substrate for the first yoke layer 22. Above the first yokelayer 22 is a second pole layer 28 which is formed with a second poletip layer 30. Sandwiched between the first and second yoke layers 22 and28 are inductive coils 32A and 32B separated from each other bydielectric material 34 (FIG. 5). The coils 32A and 32B are electricallyconnected to each other by means of an electrical feedthrough 36.Electrical current can be directed to and from the serially connectedcoils 32A and 32B via a pair of electrical leads 38A and 38B (FIG. 3).

The first and second yoke layers 22 and 28 are in direct contact at theback closure region 40 but are separated by a transducing gap layer 42at the pole tip layers 26 and 30. During the data writing mode, themagnetic head 20 flies above the surface of a recording medium 46through a thin film of air. Electrical current representative of datasignals passes through the inductive coils 32A and 32B via the leads 38Aand 38B and induces magnetic flux. The magnetic flux at the gap 42registers on the magnetic material coated on the medium 46.

During the data reading mode, magnetic flux emanating from a recordingmedium surface 46 is sensed at the gap layer 42. The magnetic fluxinduces electrical current in the inductive coils 32A and 32B, whichrepresents the recorded data. The induced current in the coils 32A and32B flows through the leads 38A and 38B for further processing.

The magnetic head 20 of the invention comprises vertically aligned sidewalls for the first and second pole tip layers 26 and 30 as shown inFIGS. 4 and 5. Specifically, the left side wall 26A of the first poletip 26 is in vertical alignment with the left side wall 30A of thesecond pole tip 30. Similarly, the right side wall 26B of the first poletip 26 is flush with the right side wall 30B of the second pole tip 30.The aligned side walls 26A, 30A, and 26B, 30B substantially reducefringing flux from one pole to another, thereby enabling the magnetichead 20 to write data with well defined data tracks on the mediumsurface 46.

FIGS. 6A-6M are sequential drawings schematically illustrating thefabrication process of the magnetic head 20 of the invention.

First a substrate 24 is provided as shown in FIG. 6A. The substrate 24can be with or without prefabricated components. A first yoke layer 22is then deposited on the top of the substrate 24 by sputtering to athickness of approximately 0.5μ-3.5μ, for example. The resultantstructure is shown in FIG. 6B.

As shown in FIG. 6C, a first pole tip layer 26 is deposited on the firstyoke layer 22 either by sputtering or electroplating to a thickness ofapproximately 0.8μ-2.5μ. Materials for the first yoke layer 22 and thefirst pole tip layer 26 are preferably materials having a high magneticmoment, such as cobalt zirconium tantalum alloy (CoZrTa), cobaltzirconium niobium alloy (CoZrNb), and iron tantalum nitride alloy(FeTaN).

A photoresist layer 48 is then patterned on the first pole tip layer 22by conventional photolithography. Thereafter, a gap layer 42 isdeposited by sputtering as shown in FIG. 6D. The photoresist layer 48 isthen removed using a photoresist solvent. The gap layer 42 deposited onthe photoresist layer 48 is lifted off along with the removedphotoresist material. The resultant structure up to this step is shownin FIG. 6E.

A second pole tip layer 30 is deposited on the structure by sputteringto a thickness of approximately 0.8μ-2.5μ, for example, as shown in FIG.6F. Another mask 50 is patterned on the second pole tip layer 30, asshown in FIG. 6G. The material for the mask 50 can be photoresist ormetal. The masked structure is then subject to an ion milling process.The mask layer 50 is resistant to milling ions. As a consequence, areasnot protected by the mask layer 50 are removed, resulting in two stacksof layers 52 and 54 formed on the substrate 24 as shown in FIG. 6H. Itshould be noted that at this juncture, the first pole tip layer 26 isseparated from the second pole tip layer 30 by the gap layer 42 in thestack 52 at the pole tip region 44. However, the first pole tip layer 26contacts the second pole tip layer 30 in the stack 54 at the back gapregion 40.

Through the process of either sputtering or plasma enhanced chemicalvapor deposition (PECVD), a protective layer 56 is deposited on thestructure with the stacks of layers 52 and 54. In the preferred method,the sputtering method is used and the protective layer 56 is depositedover and around the stacks of layers 52 and 54 to a thickness ofapproximately 3μ to 4μ. The resultant structure up to this step is shownin FIG. 6I.

The structure is then subject to a two-step leveling process in whichthe protective layer 56 is planarized via mechanical lapping with theassistance of a slurry which may include alumina (Al₂ O₃) or silicondioxide (SiO₂) for gross material removal, for example. Thereafter, ionmilling is employed for the removal of material to a fine level, therebyexposing the second pole tip layer 30. The resultant structure up tothis step is shown in FIG. 6J.

A thin layer of copper (Cu) (not shown), called the seed layer, is thensputtered on the polished surface of the structure. A photoresist mask58 is then patterned on the structure as shown in FIG. 6K.

A first coil layer 32A is then electroplated on the patternedphotoresist layer 58 as shown in FIG. 6L. The photoresist layer 58 isthereafter removed, resulting in the formation of the first coil layer32A disposed on the structure, which up to this step is shown in FIG.6M. The Cu seed layer is then etched away by lightly dipping thesubstrate with the Cu seed layer in an etchant bath filled with ammoniumpersulfate (NH₄)₂ S₂ O₈). A layer of dielectric material 60 is thendeposited on the first coil layer 32A by either the PECVD or thesputtering method. The dielectric material 60 can be selected from avariety of insulating materials, such as alumina (Al₂ O₃), silicondioxide (SiO₂), silicon nitride (Si₃ N₄), aluminum nitride (AlN) ordiamond-like-carbon (DLC). A feedthrough 62 is then formed in thedielectric layer 60 by conventional photolithography and etchingmethods, as shown in FIG. 6N. The formation of the feedthrough 62 is forthe purpose of electrically connecting the first coil layer 32A with thesubsequently deposited second coil layer 32B.

The process of forming second coil layer 32B is substantially the sameas forming the first coil layer 32A. For the sake of conciseness, theprocess of making the second coil 32B is not repeated. The resultantstructure up to this step is shown in FIG. 60.

The step of depositing a second yoke layer 28 follows. First, aphotoresist mask 64 is patterned on the dielectric material 66 as shownin FIG. 6P. Either the technique of wet etching or reactive ion beametching (RIBE) can be employed to define the apex angles α and β of thesecond yoke layer 28 as shown in FIG. 6Q. The photoresist layer 64 isthen removed. A layer of high magnetic moment material, such as cobaltzirconium tantalum alloy (CoZrTa), cobalt zirconium niobium alloy(CoZrNb), or iron tantalum nitride alloy (FeTaN) is then sputtered onthe structure as shown in FIG. 6R. Thereafter, the second yoke layer 28can be patterned via the conventional photolithography process, forexample. Shown in FIG. 3 is the plan view of the second yoke layer 28after the patterning process. After depositing an overcoat layer 68 onthe patterned second yoke layer 28, the resultant structure is as shownin FIG. 6S.

A final lapping step is performed on the tip portion 44 of the magnetichead 20 for the purpose of securing a smooth air bearing surface (ABS)70 as shown in FIG. 5.

FIGS. 7 and 8 show a second embodiment of the invention fabricated as aninverted head 72. The magnetic head 72 of this embodiment includes asecond yoke layer 74 disposed on a substrate 76. As shown in FIG. 7, thesecond yoke layer 74 is associated with a second pole tip layer 78. Aswith the first embodiment, the substrate 76 can be made of anon-magnetic and electrically insulating material such as aluminatitanium carbide (Al₂ O₃ TiC) or silicon carbide (SiC). Above the secondyoke layer 74 is a first yoke layer 80 associated with a first pole tiplayer 82. In this embodiment, sandwiched between the second and firstyoke layers 74 and 80 are inductive coil layers 84A and 84B separatedfrom each other by dielectric material 86. The coil layers 84A and 84Bare electrically connected by means of an electrical feedthrough 88.

As with the first embodiment, the second and first yoke layers 74 and 80are in direct contact at a back closure region 40. However at the poletip region 44, the first and second pole tip layers 78 and 82 areseparated by a gap layer 90. The magnetic head 72 also comprisesvertically aligned side walls for the second and first pole tip layers78 and 82 as shown in FIG. 8. Specifically, the left side wall 82A ofthe first pole tip 82 is in vertical alignment with the left side wall78A of the second pole tip 78. Similarly, the right side wall 82B of thefirst pole tip 82 is flush with the right side wall 78B of the secondpole tip 78.

FIGS. 9A-9M are sequential drawings schematically illustrating thefabrication process of the magnetic head 72.

The fabrication process starts with a substrate 76 as shown in FIG. 9A.Cavities 92 are formed in the substrate 76 by the conventional processof ion milling as shown in FIG. 9B.

A second yoke layer 74 is deposited on the substrate 92 lining thecavities 92 via the process of sputtering for example, to a thickness ofapproximately 0.5μ-3.5μ as shown in FIG. 9C. A second pole tip layer 78is then electroplated or sputtered on the second yoke layer 74 as shownin FIG. 9D.

Conventional photolithography and etching methods are employed topattern the second yoke and pole tip layers 74 and 78. Materials for thesecond yoke layer 74 and the second pole tip layer 78 are preferablymaterials having a high magnetic moment, such as cobalt zirconiumtantalum alloy (CoZrTa), cobalt zirconium niobium alloy (CoZrNb), oriron tantalum nitride alloy (FeTaN). The resultant structure up to thisstep is shown in FIG. 9E.

What follows is the formation of the first and second coil layers 84Aand 84B above the second pole tip layer 78 and in the cavities 92. Theprocess of forming the coil layers 84A and 84B is substantially the sameas the corresponding process for the previous embodiment. For the sakeof conciseness, the process is not repeated. The resultant structurewith the deposited coil layers 84A and 84B is shown in FIG. 9F.

A photoresist layer 94 is then patterned on the top of the structure byconventional photolithography. Thereafter, a write gap layer 90 isdeposited on the masked substrate as shown in FIG. 9G. The photoresistlayer 94 is then removed using a photoresist solvent. The write gaplayer 94 deposited on the photoresist layer 94 is then lifted off alongwith the removed photoresist material. A first pole tip layer 82 is thensputtered on the top of the write gap layer 90 and the second pole tiplayer 78. The resultant structure up to this step is shown in FIG. 9H.

Another mask 96 is patterned on the first pole tip layer 82. Thematerial for the mask 96 can be either photoresist or metal. The maskedstructure is then subject to ion milling. The mask layer 96 is resistantto the milling ions as shown in FIG. 9I. As a consequence, areas notprotected by the mask layer 96 are removed, resulting in two stacks oflayers 98 and 100 formed on the substrate 24 as shown in FIG. 9J. Afterthe ion milling process, the second pole tip layer 78 is separated fromthe first pole tip layer 82 by the gap layer 90 in the stack 98 at thepole tip region 44. However, the second pole tip layer 78 is in contactwith the first pole tip layer 82 in the stack 100 at the back gap region40.

Through the process of either sputtering or PECVD, a protective layer 56is deposited on the structure with the stacks of layers 98 and 100. Theprotective layer 56 is deposited over and around the stacks of layers 98and 100 to a thickness of approximately 3μ to 4μ as shown in FIG. 9K.

The structure is then subject to a two-step leveling process in whichthe protective layer 56 is planarized via mechanical lapping with theassistance of a slurry which may include alumina (Al₂ O₃) or silicondioxide (SiO₃) for gross material removal, for example. Thereafter, theion milling process is employed for the removal of material to a finelevel, thereby exposing the second pole tip layer 82. The resultantstructure up to this step is shown in FIG. 9L.

The first yoke layer 80 is then deposited on the structure by thesputtering method. The first yoke layer 80 is deposited in contact withthe pole tip layer 82 at the pole tip region 44 and the back gap region40. As with the previous embodiment, the material for the first yoke andpole tip layers 80 and 82 are preferably a material with a high magneticmoment, such as cobalt zirconium tantalum alloy (CoZrTa), cobaltzirconium niobium alloy (CoZrNb), or iron tantalum nitride alloy(FeTaN). Thereafter, the first yoke layer 80 is patterned usingconventional lithography and etching methods. The resultant structure upto this step is shown in FIG. 9M.

If the magnetic head 72 is fabricated as a merged head, the first yokelayer 80 also acts as a second shield layer. Furthermore, a readtransducer 102 and a first shield layer 104 are fabricated on the firstyoke layer 80. Fabrication processes for the read transducer 102 and thefirst shield layer 104 are conventional and need not be furtherelaborated. The resultant structure 72 fabricated as a merged head isshown in FIG. 9N.

The advantage of making a merged magnetic head as an inverted head issubstantial. In the fabrication of a magnetic head, depositing layersfor the write transducer portion, such as the coil layers 84A and 84Band the filling dielectric layer 86 very often involve high-temperatureprocessing cycles. On the other hand, depositing layers for the readtransducer 102 requires depositing and patterning of ultra-thin delicatelayers which may be detrimentally affected by the higher temperatureprocesses. Reserving the fabrication of the read transducer 102 at theend of the production process provides the benefits of preventing theread transducer from being subjected to high temperature cycles therebyimproving final production yield and reliability of the magnetic head72.

In the magnetic heads described in accordance with the invention, thepole tips are narrowly defined with aligned sidewalls, thereby enablingthe magnetic head of the invention to write on magnetic media with highareal densities. Notwithstanding the narrow pole tips, the magneticheads of the invention are less prone to run into premature magneticsaturation because the pole tips are made of high magnetic momentmaterial, thereby allowing the magnetic heads of the invention to writeon magnetic media with high coercivity and at high data rate transfer.

Other variations are possible within the scope of the invention. Forexample, the dielectric material 66 or 86 need not be alumina asdescribed. Other materials such as silicon dioxide (SiO₂) or siliconnitride (SiN), or hard-baked photoresist can well be used assubstitutes. These and other changes in form and detail may be madetherein without departing from the scope and spirit of the invention.

What is claimed is:
 1. A method of forming a magnetic head, comprisingthe steps of:(a) providing a substrate for supporting the layers of aninductive magnetic head; (b) depositing a first pole tip layer formed ofhigh magnetic moment material over said substrate; (c) depositing atransducing gap layer over said first pole tip layer; (d) depositing asecond pole tip layer formed of high magnetic moment material over saidgap layer, said first pole tip layer and said second pole tip layerformed of high magnetic moment material enabling the magnetic head towrite on magnetic media with high coercivity and at high data ratetransfer; (e) patterning a masking layer over said second pole tip layerfor ion milling and for aligning the ends of said first and second poletip layers and said transducing gap layer; (f) etching said gap layer,said first and second pole tip layers simultaneously through saidmasking layer, thereby leaving a stack of layers formed on saidsubstrate, said stack of layers comprising sections of said gap layer,said first pole tip layer and said second pole tip layer and having asurface area with ends defined by said masking layer; (g) depositing aprotective layer over and around said stack of layers, said protectivelayer being planarized and ion milled for exposing said second pole tiplayer; (h) leveling said protective layer such that said second pole tiplayer in said stack of layers is exposed; (i) patterning an inductivecoil layer above said protective layer; (j) patterning an insulatinglayer above said coil layer to insulate said coil layer from said firstand second pole layers; and (k) patterning a second yoke layer abovesaid protective layer such that a portion of said second yoke layer isin contact with said second pole tip layer for forming a magnetic path;whereby a magnetic head having narrow pole widths and high saturationthreshold levels is formed.
 2. The method of forming a magnetic head asset forth in claim 1 wherein step (a) includes providing over saidsubstrate a first yoke layer formed of high magnetic moment material. 3.The method of forming a magnetic head as set forth in claim 1 whereinstep (k) includes patterning said second yoke layer formed of highmagnetic moment material, a portion of said second yoke layer being incontact with said second pole tip layer.
 4. The method of forming amagnetic head as set forth in claim 1 wherein step (f) includes etchingsaid gap layer and said first and second pole tip layers through saidmasking layer by ion beam etching.
 5. The method of forming a magnetichead as set forth in claim 1 wherein steps (b) and (d) includesputtering said first and second pole tip layers on said substrate andsaid gap layer, respectively.
 6. The method of forming a magnetic headas set forth in claim 1 wherein said first and second pole tip layersare formed of a material selected from a group consisting of cobaltzirconium tantalum alloy, cobalt zirconium niobium alloy, and irontantalum nitride alloy.